Fantasy world not reincarnation, transmigration or summon

She says she possessed the body of a character in her novel she wrote when she was younger

Kicked off the party, mc starts his new adventure

Opens door from the inside to a dungeon

Assassin

Ohhh, this is the one who's a beast tamer but his beasts are weak.... Then he forms a contract with a beastgirl

COLLECTing demon spirits... I think that's his harem